Surface and interface effects on a magnetic Chern insulator

TL;DR

This paper investigates how surface and interface effects influence the magnetic and topological properties of a magnetic Chern insulator, revealing controllable edge states via magnetic junctions.

Contribution

It introduces a simple junction model to describe edge reconstruction and demonstrates magnetic control of topological edge states in magnetic Chern insulators.

Findings

Edge reconstruction enhances chiral edge current.

Magnetic capping layers can modulate edge states.

Surface effects lead to nontrivial surface reconstructions.

Abstract

Effects of an open surface on a magnetic Chern insulator are investigated in comparison with those of an interface to a capping magnetic layer. In magnets, an open surface often perturbs the magnetic order by a reconstruction of the magnetic moment directions near the surface. On the other hand, in topological insulators, it leads to the formation of topologically protected surface states. These two contrasting effects may coexist in magnetic Chern insulators, which give rise to nontrivial surface reconstruction. For instance, the chiral edge current is largely enhanced by the edge reconstruction in a two-dimensional magnetic Chern insulator realized in a quarter-filled Kondo lattice model on a triangular lattice. We here show that the edge reconstruction can be described semiquantitatively by a simple junction model between the bulk topological magnetic state and a ferromagnetic capping layer. We further clarify how the chiral edge current is affected by the magnetic structure in the capping layer. Our results indicate that the topological edge state can be controlled magnetically through the junctions.